Thermostatic control



; Oct. 29, 1935. J. LITHGOW ET AL 2,019,472 THERMOSTATIC' CONTROL FiledMarch 21, 1954 s Sheets-Sheet '1 3 Sheets-Sheet 2 J LITHGOW ET ALTHERMOS'IIATIC CONTROL Flled March 21, 1954 Oct. 29, 1935. J. LITHGOW ETN. 2,019,472

THERMOSTATIC CONTROL Filed March 21, 1934 3 Sheets-Sheet 3 Patented Oct.29, 1935' THERMOSTATIO CONTROL John Lithgow, Blue Island, and Gordon E.Gray, Chicago, 111., assignors to North American Car Corporation,Chicago, 111., a corporation of lllino Application March 21, 1934,Serial No. 716,584

25 Claims. (Cl. 236-4) Our invention relates in general to temperaturecontrol and has more particular reference to improved meansfor andmethod of controlling devices operating in response to temperatureoperation in accordance with temperature conditions prevailing'at acontrol station, which control means is flexible and may be applied tovarious types of apparatus to be controlled and conditions prevailing atany control placeor adapted to a'variety of control'conditions and 5station, the invention relating more especially to which permits theselection of any one of a plu-. the control of air tempering apparatusin order rality of temperature ranges within which it is to maintain atreated atmosphere within prededesired to selectively control one orseveral determined temperature limits, and having specific, vicescomprising the controlled apparatus.

application to the automatic control of tempera- Another importantobject of the invention is 10 ture conditions in moving vehicles. toprovide means for selectively controlling the An important object of theinvention is to operation of air tempering apparatus within a provideadjustable means for the control appapredetermined temperaturedifierential at difratus in response to temperature conditions, ferenttemperatures within a predetermined which means may be adjusted bysimply moving range. 15 a pointer on a scale without reliance upon theAnother important object resides in the proviskill of an operator. sionof the novel method of controlling air tem- Another important object isto provide control pering apparatus as exemplified in the followingmeans for any apparatus, more especially air description.- temperingapparatus, which operates in accord- These and numerous other objects,inherent 20 ance with temperature conditions prevailing at advantages,and functions of the invention will a control point or station whichcontrol means be apparent as the invention is more fully underispositive in operation, rugged and relatively stood from the followingdescription, which, inexpensive, easy to install and service, flexibletaken in connection with the accompanying to afford a variety of controloperations, and drawings, discloses preferred embodiments of the 25which is not susceptible to faulty operation due to vibration such as isencountered in vehicles.

Another important object is to provide readily adjustable means forcontrolling the operation of air tempering apparatus withinpredetermined temperature range.

Another object of the invention is to provide adjustable means forcontrolling the operation of any apparatus, more especially airtempering, apparatus, adapted to be operated in accordance withtemperature fluctuations at a control station wherein the operator mayadjust the tern-j perature range within which the control is desiredwithout interfering with the operation or adjustment of the apparatusitself, thus permitting the apparatus to be permanently adjusted foroperation by the manufacturer or by an expert service man, and to remainin adjusted conthe drawings, apparatus 9, namely, an-air teminvention.

Referring to the drawings:

Figure 1 is a sectional view taken longitudinally through a vehicleprovided with 'air tempering apparatus adapted to be controlled in 30accordance with the teachings of the present invention;

Figure 2 is a view of theunderside of the vehicle shown inFigure 1 inorder to more fully illustrate the arrangement of parts of the air 36tempering apparatus;

Figure 3 is a diagrammatic view of the air tempering apparatus shown inFigures 1 and 2, together with an automatic control system em- I bodyingthe presentinventiontand 40 Figures 4, 5, 6, and '7 illustrate modifiedarrangements of a part of the control system illustrated in Figure 3.

To illustrate our invention we have shown on 45 pering system, theoperation of which, in accordance with the fluctuation of temperature ata. control station, is desirable. 'The apparatus to be controlled isprovided with a readily-adjustable control system III which embodies andoperates in accordance with, the teaching of our present invention. Theapparatus to be controlled and the control means are shown mounted in avehicle, namely a railroad refrigerator car, although it is obvious thatthe present inven- BI tion is not necessarily limited to installationsin vehicles or to air tempering apparatus but may be applied for thecontrol of any operating device or apparatus whether on a vehicle orinstalled for stationary operation.

As shown inthe drawings, however, we prefer to apply the control meansof our present invention for the control of air tempering apparatuscarried in a vehicle l| comprising a preferably insulated housing orcasing forming a compartment l2, the atmosphere within which'is to betempered. In the illustrated embodiment, the casing or housing comprisesthe body of a railroad refrigerator car having wheels l3 and the airtempering apparatus includes a refrigeration system of thecompression-evaporation type, in which a suitable refrigerating mediumsuch as ammonia, sulphur, dioxide, ethyl chloride, or other suitablemedium may be circulated from a compressor l5, in which the,refrigerating medium, in gaseous condition is compressed, through acondenser H, in which the compressed medium is liquefied, an expansionvalve l9, and a selector valve 2| through which the liquefied medium isor may be selectively delivered either to direct cooling coils 23 or tocold storage devices 25 located in any suitable or convenient positionin or on the casing in heat exchange relationship with the atmosphere ofthe compartment I2. The expansion valve IS, in the illustrated system,is preferably of the float controlled type. The coils 23 compriseevaporators or boilers in which the liquefied refrigerant may evaporatein order to absorb heat from and thus refrigerate the surroundingatmosphere while the cold storage devices comprise evaporator coilsimmersed in brine or other cold storage medium. The gas, produced by theevaporation of the refrigerating medium in the coils of the cold storage device 25 and in the direct-cooling coils 23, is or may be returned,by means of a common return pipe 21 to the suction side of thecompressor I5 so that the refrigerating apparatus may functioncontinuously as long as the compressor is driven- The coils 23 and coldstorage devices 25 may be located on the side walls or roof of thecompartment, or in any other suitable position in the compartment l2,but are preferably disposed at opposite ends of the compartment behindpartitions or bulkheads |4 spaced from the ends of the compartment toprovide air conditioning chambers I6 and the bulkheads preferably haveopenings [8 and 20 respectively near the ceiling and the floor of thecompartment to facilitate the circulation of air between the compartmentl2 and the cooling chambers IS. The directcooling coils 23 and coldstorage devices 25 are also preferably arranged for parallel operation,the temperature-regulated control valve 2| being provided to direct theflow of the refrigerating medium either to the refrigerating coils 93 orto the cold storage devices 25.

Any suitable means for driving the compressor may beemployed, althoughwe prefer to utilize electrical power supplied. from any suitable orconvenient source or sources. To this end, We have shown an electricmotor 49 drivingly connected with the compressor and together with thecompressor mounted on a-frame 41 carried beneath the compartment l2. Themotor 49 is electrically connected in series with atemperature-controlled switch 53 between bus conductors 55 and 51,which, in turn, are connected with a power source 59 on the vehicle. Thepower source is or may be a generator carried by the vehicle and drivenin any suitable fashion when the vehicle is in transit to deliverelectrical power between the bus conductors 55 and 51. When the vehicleis stationary, the generator may be 5 driven in any suitable fashion asby a motor adapted to be energized from an external source of powerthrough a suitable plug-in connection, and the motor and generator 59may be built as a unit, if desired, or means may be provided for 1()supplying power from an external source directly to the bus conductors55 and 51, and while any type of electrical power may of course beutilized, we prefer to supply direct current at the conductors 55 and51. 15 The switch 53 is normally biased, as by means of a spring, toopen position, and has an operating solenoid 54 which when energized,will cause theswitch to close and connect the motor between the powerbusses 55 and 51 and thus place 20 the refrigerating apparatus inoperation. A blower and motor 5|) for forcing a draft of air to thecondenser may also be provided, the motor 50 being connected in parallelwith the motor 49 to operate the fan whenever the refrigerating 25apparatus is in operation.

The selector valve 2| also is normally biased to deliver the refrigerantfrom the condenser to the cold storage devices 25 but is provided with asolenoid 31 which, when energized, causes the 30 selector valve todeliver the refrigerating medium from the condenser to the directcooling devices 23. When the direct cooling devices 23 are in operation,the cooling effect of the refrigerating apparatus is imparted, to theatmosphere of the 35 compartment |2, more rapidly than when therefrigerating medium is delivered to the cold storage devices, thepurpose of the cold storage devices being to store potentialrefrigerating energy for gradual liberation during the interval when 40the maximum heat absorbing capacity of the cooling apparatus is notneeded to maintain the temperature of the compartment within a desiredlimit. One end of the solenoid 31 is connected with the bus conductor 51and the other end is connected through a switch 39 to the other busconductor 55. The switch 39 is normally biased as by means of a springto open position and has an operating solenoid 4|, which, whenenergized, causes the switch 39 to close against its spring bias. Whenthe solenoid 4| is energized, the closure of the switch 39, will causethe solenoid 31 to be energized which in turn, will condition the valve2| to deliver the refrigerating medium to the direct cooling coil.Conversely when the solenoid 4| is not energized, refrigerating energy,will be delivered to the cold storage device for delayed liberation tothe atmosphere of the compartment.

The air-tempering apparatus also includes 00 heaters 35 preferablyarranged for parallel operation and disposed at opposite ends of thecompartment |2 in heat-exchange relationship with the atmosphere of thecompartment, the heaters being preferably disposed on or near the floorof the compartment in position to dissipate heat upwardly by convectionin the compartment. One end of each heater is connected with the busconductor 51, the other ends'of the heaters being connected together andthrough a control switch 63 to the other bus conductor 55. The switch 63is normally biased as by means of the spring toward closed position, andhas a solenoid 65, which causes the switch to open whenever the solenoidis energized. 76

The air tempering apparatus also may include blowers 3| for assisting inthe circulation of air between the compartment I2 and-the coolingchamberI6, said blowers being preferably located at the opposite ends of thecar near the openings I8 at the upper-end of the partitions I4. Theblowers are powered by electric motors preferably connected in parallelwith the solenoid 31 so that the blowers are placed in operationwhenever the direct cooling coils are in operation, that is, whenmaximum cooling effect is desired; The blowers operate to draw air fromthe compartment I2 through the openings 20 past the cold storage deviceand direct cooling coils and return the refrigerated air to thecompartment I2 through the upper openings I8.

Although our control system is particularly adapted fort he control ofrailway refrigerator cars, it has broader scope, and we have shown anddescribed the foregoing air tempering apparatus not necessarily by wayof limitation, but to furnish a basis for disclosing the operation ofthe control system which we are about to describe, and it should beunderstood that the invention is not necessarily limited to the controlof air tempering apparatus, but may be applied to any device or devices,the operation of which is to be controlled in accordance withtemperature conditions prevailing at a control station. It will beapparent, however, that the control of the apparatus is accomplished byselectively controlling the operation of the solenoids 4 I, 54, and 65,which therefore comprises controlled devices 66, and our presentinvention resides in adjustably controlling the devices 66, selectively,in accordance with fluctuating temperatures prevailing at a controlstation, which, in the illustrated embodiment is the compartment I2, andthe device of our present invention contemplates the selective controlof the devices 66 whether or not they are switches, as shown, and as faras the broad aspects of our invention are concerned, it is, of course,immaterial whether the devices 39, 53 and 63 controlled by the devices66 are biased in one direction or another.

In order to control the operation of the devices 66 in accordance withthe temperature prevailing at the control station or compartment I2,whereby the heaters and the cooling devices, comprising the controlledapparatus 9, may be selectively operated to add heat to and subtractheat from the atmosphere of the compartment in order to maintain thetemperature thereof within predetermined limits, we have provided acontrol system I0, manually adjustable, without interfering with theoperation of the apparatus 9, in order to afford a wide selection oftemperature ranges within which it may be desired to maintain thetemperature within the compartment I2. To this end we have provided aplurality of thermoresponsive devices 61 preferably comprising contactmeans 69 adapted to close each at a different predetermined or settemperature prevailing at the control station, said contacts remainingclosed each as long as the temperature at the control station is aboveits set temperature, and remaining open as long as the temperature isbelow the set temperature. The

3 posed at various points in the length of the thermometer channel,whereby the expansible medium, in traveling the channel, in response tovariations in the temperature to which the thermometer is exposed, willsuccessively engage and 5 make electrical contact with the exposedterminals. These thermoresponsive devices are, or may be mounted, as ona panel 64, within the compartment I2, in heat exchange relation withthe atmosphere therein. 10 An adjustable selector 68, having a pluralityof contacts I0, preferably arranged as in sets II-99, is provided foruse in conjunction with the thermoresponsive switches 69 in order to aselect and connect the desired switches in circuits 15 controlling theoperation of the devices 66. Each contact set II99 preferably containscontacts equal in number to the number of devices 66, the operation ofwhich it is necessary to control in order to control the operation ofthe air-tempering 20 apparatus, and it should be understood, of course,that our invention may be applied to apparatus containing any desirednumber of devices 66 to be controlled. Each of the thermostat contactsisconnected with a corresponding contact of the 25 selector 68 and theexpansible medium, which is an electrical conductor, such as mercury, ispermanently connected with the bus conductor 51 by means of a busconnector I 89. As shown in Figure 3, a separate thermometer may be usedfor 30 each contact set of the selector, the expansible medium of eachthermometer being permanently connected with the bus conductor 51. Eachthermometer has contacts exposed in the channel thereof and each contactis electrically connected 35 with a corresponding contact of the setwith which the thermometer is associated. Alternately, a separatethermometer may be provided for each contact III, or, as shown in Figure4, a single thermometer may be used for all of the 40 sets or some ofthe contacts of each set may be connected to the same thermometer whilethe other contacts are connected to other thermometers. We prefer to usethermometers having three contacts 69 in addition to the contact 45 bywhich the expansible medium is connected in the return circuit I89. Thethermometers also are made with an expansionchamber at their upper endto permit the thermometers to be made relatively short with relativelywide spacement 50 between the contacts 69 without danger of explodingthe thermometers at temperatures higher than their operating range.

The selector switch 66 is also provided with a plurality of shiftablecontactors I00, which are 55 preferably ganged together for synchronousmovement and to selectively engage with any employed. Each of thecontactors I00 is elec-,

trically connectedby means of a suitable conductor with one end of oneof the operating solenoids 65 4 I, 54, and 65, contactor IOI beingconnected with solenoid 4|, contactor I02 with solenoid 54, andcontactor I03 with solenoid 65. Theopposite ends of the solenoids aredirectly connected with the bus conductor 55 so that the solenoids maybe 70 selectively connected in operating circuits extending between thebus conductors 55 and 51, each said circuit including one of thesolenoids 66, one of three adjacent terminals I0 of the selector 68 andits associated-thermostat, merely by shift- 75 ing the contactors I intoengagement with the desired terminal set. While we prefer to form theselector 68 as a rotary switch in which the contacts I0 are arrangedcircularly while the contactors I 00 are mounted for movement with arotating knob I04 having a pointer I05 to indicate the setting of theknob, the contactors may be arranged to shift in any desired orpreferred path.

In the illustrated embodiment, the contacts of the sets I I, I2, and I3are each connected through thermoresponsive switches 69 with the busconductor 51.

' and two contacts of the sets lit-9| are connected through a,thermoresponslve switch with the bus conductor 51, the remainingcontacts ofs'aid sets being connected either directly to the busconductor 5I orleft open. as shown. All of the contacts of the set 92,the first two contacts of the set 93, the first contact of the set 94,none of the contacts of the set 95, the last contact of the set 96, thelast two contacts of the set 91, the first and last contacts or the set98,-.and the middle contact of the set 93 are or may be directlyconnected wlfih the bus conductor 51, the remaining contacts of saidsets being left open. By manipulating the contactors I00 into engagementwith the contact sets I I99, a variety of control circuits for thesolenoids may be established. If the contactors I00 are engaged with thecontacts I0, which are connected with thermostats, circuits will beestablished, each circuit extending from the, bus conductor through oneof the solenoids 4|, 54, and 65, one of the contactors I00, theterminal-engaged by said contactor, thence through the thermostatassociated with said terminal and the bus connector 89 to the busconductor 51. the thermostat included therein closes, will energize thesolenoid which is included in the circuit, and the solenoid will performa control operation on the apparatus with which it is associated. Whenthis occurs in a circuit including the solenoid 65, the normally closedswitch 03 will open and discontinue the heaters from operation whenever.the temperature in the compartment rises above the point at which theheater control thermostat closes. As long as the temperature remainsbelow such point, however, the control circuit remains open with thesolenoid remaining de-energized, the switch 03 closed and the heaters inoperation. If the temperature continues to rise after thediscontinuation of the heaters, the thermostat in the circuit, includingthe solenoid 54, will eventually close and complete said circuit betweenthe bus conductors 55 and 51, thus energizing the solenoid 54 andclosing the switch 53 to place the motor in operation to drive therefrigeration apparatus with the valve 2| conditioned to pass therefrigerating medium to the cold storage, on slow cooling, devices 25.If the temperature continues to rise after the refrigerating apparatusis thus placed in operation, the, thermostat in the circuit controllingthe solenoid 4| will eventually close and complete said circuit betweenthe bus conductors 55 and 51, thus energizing the solenoid 4| andcausing the valve to deliver the refrigerating medium to the directcooling devices to thus deliver the maximum cooling capacity of theapparatus directly to the chamber I2. Upon a fall in temperature withinthe compartment I2, theope'ning of the thermostat contacts in thesolenoid control circuits successively cause the switches 39 and 53 toopen, thus discontinuing the direct One contact only of the sets 14-85Each of said c'rcuits, wnen the heaters again in operation. Thus it willbe seen that the air tempering apparatus will be automaticallycontrolled to add or subtract heat 5 from the compartment I2 in order tomaintain the temperature of the atmosphere within a range depending uponthe adjustment of the thermostat devices associated with the contactsopposite which the contactors 8| are set. 10 It will be apparent alsothat, where the control isapplied to a device such as the refrigerationsystem shown, it is desirable to ensure that the thermostat controllingthe solenoid'65 is adjusted to close circuit at a temperature below 15that at which the thermostat controlling the solenoid 54 closes circuit,and that the thermostat controlling the solenoid 54 closes circuit at atemperature below that at which the thermostat controlling the solenoid4| closes circuit. 20

We accomplish this by gauging the contactors I00 and by connecting thecontacts I0 with the thermostat devices in such a way that in any setposition of the selector, the contactor II, which is connected with thesolenoid 4|, can only en- 25 gage a contact I0 which is connected with athermostat closing at a temperature higher than the closing temperatureof the thermostats to which the other contactors I02 and I03 areconnected when in said set position of the selector, 30 while thecontactor I03, which is connected with the solenoid 65 in any setposition or the selector, can only engage a contact 10 connected with athermostat closing at a temperature lower than the closing temperaturesof the thermo- 35 stats to which the other contactors IIII and I02 areconnected.

The thermostat devices, connected with the several terminal sets I. -I,I2, and I3, are calibrated to cause operation of the devices 4|, 54 and05 40 within different ranges or temperature so that by setting thecontactors I00 opposite the proper terminal set of the selector, thedevice may be set to operate within any desired temperature range withinthe limits or the control device.

If any of the contactors I00 engage a terminal I0 which is connecteddirectly to the conductor and thence to the bus conductor 51, it isobvious that a circuit will be established which will energize thesolenoid included in that circuit 50 continuously and regardless of thetemperature within the compartment I2; while if any 0! the contactorsI00 engage a terminal I0 which is not connected either toa thermostat orto the return conductor '80, the solenoid controlled by 55 suchcontactor will at no time be energized. Thus, the device is selectivelyoperable to provide various control combinations and may be instantlyadjusted to provide full automatic temperature control of all thedevices 68 and the co apparatus controlled thereby, or to provide forthe temperature control of any or the devices or any combination or thedevices, and to provide for maintaining any ot'the devices orcombinations of the devices either permanently inactive 65 orpermanently in operation without temperature control.

It will be noted that when the contactors I 00 are engaged with any ofthe sets", I5, I6, and II, the contactor IOIonly is connected with a 70thermostat device, the remaining contactors being connected eitherdirectly to the bus conthe arrangement of set 14 is applied to controlthe apparatus 9, the solenoids and 54 are at all times energized,maintaining the switch 53 ating medium is delivered to the cold storagede vice as long as the temperature in the compartment remains below thepredetermined value represented by the position of the terminal con tactin the channel of the thermometer. Whenever the temperature rises abovesuch a value,

the refrigerating medium is, by the operation of the switch 39,delivered to the direct cooling coils 23 in order to apply maximumrefrigeration to the compartment.

When the contactors I00 engage the contact set l5, it will be seen thatthe solenoid 4| will be energized under thermostatic control, while'heaters and the cooling system simultaneously.

The contact set 15 is therefore omitted from the control system shown inFigure 4, but is shown in Figure 3 to indicate its possible utility incontrolling other apparatus than that shown in Figure 4.

When the contactors I00 engagethe contact set '16, it will be seen. thatthe solenoid 4| will be energized under thermostatic control while thesolenoid 54 is always idle, the solenoid 65 being always energized. Suchan arrangement also is'impractica-l for use in controlling air temperingsystem 9, since the heater and refrigerator would both be permanentlydisabled withthe valve 2| under thermostatic control.

In like manner the contact set 11 would serve no useful purpose ifapplied to control the device shown in Figure 4, since it would keep theheaters continuously on and the refrigerator continuously off with thevalve 2| under thermal control. No useful purpose is served inmaintaining the valve 2| under control, in the air tempering system ifthe refrigerator is inactive to circulate the medium. The control setsI6 and 11 are therefore omitted from the control shown in Figure 4, butare shown in Figure 3 to indicate the possibility of using them forcontrolling other apparatus than that shown in Figure 3.

When the contactors I00 engage any of the contact sets I88|, thesolenoid 54 is under thermal control, and the solenoids 4| and 55 areeither permanently active or permanently disabled. In the set 18, thesolenoids 4| and 65 are directly connected with the bus connector 51,and will be constantly energized so that the switch 63 is constantlyopen and the switch 39 constantly closed. Consequently, the heaters willat all times be inoperative while the selector valve 2| will at v alltimes be set to deliver refrigerating medium to the direct coolingcoils. The solenoid 54, how- ,ever, is under the control of thethermostat to will close and set the refrigerating apparatus inoperation with refrigeration accomplished by the direct cooling coilsonly. This is a suitable control for the air conditioning system 9, andis therefore shown in Figure 4 as well as in Figure 3. 6

In the set I9, solenoid 4| is permanently in-- active while the solenoid65 is always energized, the solenoid 54 being under thermal control.This set also may be used to control the air tempering system 9, sinceit holds the heaters perlo manently ofi with the refrigerator operatingunder thermal control to deliver the cooling medium to the cold storagedevices. 7

In the set 80, solenoid 4| is permanently active while the solenoid 65is inactive, solenoid 54 being 15 under thermal control. In theset 8|,the solenoids 4| and 85, are permanently disabled, while the solenoid 54operates under thermal control. Both of these arrangements areundesirable for controlling the apparatus 9, since it would cause 20 therefrigerator to operate at times simultaneously with the heaters.Consequently, these sets are omitted from the control shown in Figure 4.

If the contactors engage any of the contact sets 82-85, temperaturecontrol is applied to the 28 solenoid 85 only through the contactor I03,and the solenoid is energized whenever the thermostat contact with whichit is connected is closed, thus opening the switch 63 and discontinuingthe heaters from operation when the temperature-is above that at whichthe thermostat contact closes. Of these sets 82-85 the set only isadapted to be applied to the apparatus 9, the other sets beingundesirable; set 82 because it would continuously energize solenoids 4|and 54, and thus 85 keep the refrigeration apparatus in operationcontinuously with the medium being delivered to the,direct coolingdevice 23, and at times cause the heaters to operate; the set 83 becauseit would continuously energize the solenoid 4 I, the solenoid 74o ouslyenergize the solenoid 54 and operate the 45 refrigerator, the solenoid4| being inactive with the solenoid 65 controlling the heaters underthermal control, so that the heaters would be at times in operationtogether with the refrigerator.

These sets 82-84 are therefore not shown in the 80 control illustratedin Figure 4. The set 85, however, may be used to control the apparatus9, Y since it will keep both solenoids 4| and 54 inactive, thusdisabling the refrigerator while keeping the solenoid 85 and the heaterscontrolled there- 65 by under thermostatic control.

If the contactors I00 engage any of the sets as a|, two of the devicesas will be operated automatically under thermostatic control while thethird will be either permanently active or 80 disabled, depending 0 11whether the third contact 10 of the set is connected to the returnconductor 89 or left open. In sets 86 and 81 the solenoids 4| and 54 areoperable under thermostatic control, in sets 88 and 89 the solenoids 4|and 65 65 are thermostatically, controlled, while in sets. 90 and'9l thesolenoids 54and 65 are under thermotatic control. In set the solenoid 55is permanently active, while in set 8'l'it is inactive. In set 88 thesolenoid 54 is permanently active, while 70 in set 89 it is permanentlydisabled. In set 90 the solenoid 4| is permanently energized, while inset 9| it is inactive.

The sets 86, 90, and 9| are suitable for Inclusion in control for theapparatus 9, and are shown 7 in Figure 4 since the set 86 will hold theheaters inactive while permitting the refrigerator and valve 2| tooperate under thermal control; the set 99 will permit operation of bothheaters and refrigerator to operate under thermal control with the,cooling units 23 only in operation; and the set 9| permits thermallycontrolled operation of the heaters and refrigerator with cooling units25 only in operation.

The sets 81,88 and 89 are not suitable to the control of the apparatus 9and are omitted from Figure 3, since set 81 provides for thermal controlof solenoids 4| and 54 with solenoid 64 permanently disabled, while set88 provides for the thermal control of solenoids 4| and 65 with solenoid54 in constant operation. Either set ap-- plied to th a control ofapparatus 9 would, at times, cause simultaneous operation of the heatersand refrigerating apparatus. The set 89 causes the solenoids 4| and 65to operate under thermal control while solenoid 54 is disabled, and ifapplied to control the apparatus would waste power in the solenoid 4| tokeep the valve 2| open to the devices 23 when the solenoid 54 isinactive, and the refrigerator disabled.

Obviously, it is within the scope of the invention to provide a selectorto serve given conditions, having any or all of the sets '||99.

It is also within the invention to connect all of the contacts of a setdirectly with the bus conductor 51, and in. certain instances to omitcertain of such direct connections altogether as in the sets 92-99 inorder to entirely eliminate the temperature control of the solenoids,and while certain of such arrangements are not desirable in acontrol-for use with the air tempering system illustrated, they are allwithin the contemplation of our present invention and may be used toadvantage under certain conditions. The sets 92 through 99 illustratethe possibility of connecting one or more of the terminals of each setdirectly with the bus conductor 51. In the set 92, all of the contactsare connected directly with the return conductor, so that all solenoidsare energized continuousl This set may be applied in a control for theapparatus 9 as shown in Figure 4, since it will hold-the heaterspermanently inactive while causing the refrigerator to operate thedirect cooling coils 23 only. In the set 93, the first two contacts areconnected directly with the but conductor 51, while the third contact isisolated. If the contactors I99 are engaged with the contacts of the set93, the solenoids 4| and 54 will be continuously energized and thesolenoid 65 will be inactive at all times. Such a set should not be usedto control the apparatus, because itwould cause the refrigerationapparatus to' be inconstantoperation with the medium being deliveredthrough the direct cooling coils and at the same time cause the heatersalso in continuous operation. The arrangement of the set 94 is such thatthesolenoid 4| will be continuously energized while the solenoids 54 and65 will. not be energized at any time. This set also is not adapted foruse with the apparatus 9, since such use would cause the heaters to bein constant operation with the refrigeration device, and would beinactive with power delivered to the solenoid 4| irl order to conditionthe valve 2| to deliver the refrigerating medium to the direct coolingcoils. It would serve no good purpose to so waste power at the solenoid4| when the refrigerator is inactive. The terminals of set 95 are allisolated so that when the selector is adjusted to this position, none ofthe solenoids 4|,

54 and 65 can be energized at any time, and 11' the set is applied tocontrol the apparatus 9, the heaters only will be in constant operation.The arrangement of the set 96 is such that the solenoids 4| and 54 are,at all times, inactive while the solenoid 65 is continuously energized.This arrangement may be used in the control-for apparatus 9 since, inthis position, the heaters are held inactive while the refrigeratingapparatus is also held inactive. The arrangement of the contact set 91is such that the solenoid 4| is inactive while the solenoids 54 and 65are energized at all times so that the heaters are inactive while therefrigerating apparatus is constantly in operation with the valve 2|delivering the refrigerating medium to the cold storage device.

In the set 98 the first and last terminals are connected to theconductor 89 so that the solenoids 4| and 65 are constantly energizedwhile.

the solenoid 54 is disabled. If this set was applied to the apparatus 9,the heaters and refrigerator would both be inoperative with the valve 2|set to deliver the refrigerant to the coils 23, and since no goodpurpose is served in wasting power in the solenoid 4| when therefrigerator is disabled, the set 98 is not shown in Figure 4. In theset 99 the middle contact only is connected to the return conductor sothat the solenoid 54 only is energized. This set also is not shown inFigure 4, for if it were applied to the apparatus 9, the heaters andrefrigerator would be in constant operation.

In building a selector for the air tempering apparatus shown, it isdesirable to use one or more of the contact sets 1|, I2, 13, I4, 18, I9,85, 86, 90, 9|, 92, 95, 96, and 91. These sets afford the followingselective control arrangements:

Control Contact set Refrigerator Cooling devices Heat 71, 72, 73. Fullthermal control of all units within the range 0| the respective sets. 74On Selective thermal 011.

control. 78 Thermal control. On direct cooling...- Off. 79 Thermalcontrol. On cold storage"... 08. 0 Thermal control 86 Thermal control...Selective thermal control. 90 Thermal control... 011 direct cooling. Theimlal con to 91 Thermal control--- On cold storage. T h e r in a]control 92 On on direct cooling.-. Off. 95. OH On. 96. Off Off. 07 0n Oncoldstorage 0|].

In Figure 5 of the drawings, I have shown the possibility ofre-arranging and equally spacing the contacts 19 in order to utilizefewer contacts in providing the set combinations shown in Figure 3, andat the same time to increase the flexibility of thermal control throughthe possibility.

of utilizing any three of the terminals instead of any three forming adefinite set as in Figure 3. For instance, the contacts affording thethree control positions corresponding to sets H, 12,

and 13 in Figure 3, are, in the arrangement shown in Figure 5, no lessthan seven full thermal control positions, while the first and last twocontacts of these sets cooperate with other contacts to give fouradditional positions aflordthe central contactor I02 opposite the propercontact of the arrangement shown in Figure 5, with the-contactors IOIand I03 in engagement with the next adjacent contacts. Thus a greatflexibility of control is provided with few contacts.

In Figure 6 of the drawings, a selector I08, similar to the selector 68,is used in conjunction with a selector I09. All of the contacts I0 ofthe selector I08 are connected to thermostats, and

the two selectors operate together to provide more flexible operation ofthe system. The selector I09 in the embodiment shown in Figure 6 isinterposed between the selector I08 and the solenoids 4|, 54, and 65,the operation of which is to be controlled. The contactors IIO oftheselector I09 are connected respectively to the solenoids 4|, 54, and 65,while the contacts I0 of its several sets I2II32 are connected to thebus connectors I33, I34, I35, I36, which are in turn connectedrespectively to the contactors I0 i, I02, I03 of the switch I08, and tothe bus connector I09 and bus conductor 51. The contactors of theselector I08 can be positioned to connect the conductors I33, I34, andI35 to any three of the thermal switches 69 with which it is associated.When the contactors IIO are arranged opposite the contact set I2 I, thesolenoids 4i and.

64 will be permanently disabled while the solenoid 65 will be energizedunder thermal control of the thermal switch to which the contactor I03is set. The air tempering system will opcrate with the refrigeratorpermanently off, and the heaters operating under thermal control. Whenthe contactors IIO engage the contact set I22, the solenoids 4| and 54will be permanently disabled, while the solenoid 65 will be permanentlyactive, and the air tempering apparatus will be dead. The set. I23affords full thermal control of the heaters, refrigerator and theselector valve 2|, all solenoids being energized under the control ofthe thermal switches to which the contactors 'IOI, I02 and I03 areconnected.

The set I24 affords thermal control of the operation of the refrigeratorwith refrigerant delivered to the direct cooling coils, the heatersbeing permanently disabled. The set I25 places the refrigerator incontinuous operation with refrigerant delivered to the direct coolingcoils and heaters permanently disabled. The set I26 affords thermalcontrol of the heaters and the refrigerator with refrigerant deliveredto the cold storage devices. The set I2'I aifords thermal control of therefrigerator with refrigerant delivstorage and direct cooling devices,while the heaters will be inoperative at all times. The set I30 placesthe refrigerator in constant operation with the refrigerant delivered tothe cold storage device, the heaters being held permanently idle.-

The set I3I places the refrigerator in operation under thermal controlwith the refrigerant delivered to the cold storagedevice, and theheaters being held permanently idle. The set I32 places the, heaters inpermanent operation while holding the refrigerator inactive.

While the arrangement shown in Figure 6 contains only such sets as areparticularly useful in controlling the apparatus 9, it is obvious thatit.

can be made to provide any and all of the set combinations suggested inFigure 3. The contact sets of the selectors I08 and I09 also may beconde'nsed as taught in connection with the device shown in Figure 5.vWhile'we have shown in Figure 6 a number of possible set combinationswhich might be used in controlling the air tempering apparatus 9, it isobvious that several of the .set combinations may be eliminated entirelyand yet afford a control flexible enough for most practical purposes.For instance, the selector I09 may be built with only the followingsets:

It will be noted that the temperature differentials, within the limitsof which the apparatus is controlled, are fixed by the thermostats. Theuse of adjustable thermostats is, of course, within the contemplation ofour present invention, but we have shown fixed thermostats comprisingthermometers having contacts 69, and our present invention isparticularly adapted to give wide flexibility of control using thermalswitches fixed, to open and close circuit, each ata predeterminedtemperature. I

We have shown in Figure '7, a system which affords flexibility over awide range as well as the added advantages of adjustability of thetemperature differential, and the ability to cause the control switchesto operate at any temperature within the range for which the apparatusis adapted without regard to the temperature at which any of the othercontrol switchesoperate. In certain cases, it is preferable topositively prevent one or more of the switches from operating at atemperature above or below any other switch as is the case in thecontrol of the air tempering apparatus 9. Consequently, in the controlshown in Figures 3, 4, 5, and 6, the control device is arranged so thatthe switch 39 may close only at a temperature above that at which theswitch 53 closes, while the switch 63 may close only at a temperaturebelow that at which the switch 63 opens, regardless of the adjustment ofthe selector. Of course, the thermal switch may be other-- wiseconnected to the contacts in the devices shown in Figures 3, 4, 5, and6, in order to provide greater flexibility of control. However, whenmaximum flexibility is desired, we may provide it separately operableselector for each of the devices to be controlled. To this end, we haveshown a selector switch I33 for the solenoid 4 I, a selector switch I35for the solenoid 54, and a selector I31 for the solenoid 65. Theseswitches'each have a plurality of contacts I40-I 52 arranged preferablycircularly and a shiftable arm is provided'in position to successivelyengage the contacts, the shiftable arm of the switch I33 being connectedto the solenoid 4|, the arm of the switch I35 being connected to thesolenoid 54, and the arm of the switch I31 being connected to thesolenoid 65.

The corresponding contacts MD of the switches I33, I35 and I3I areelectricallyconnected together and connected to the bus conductor 51.The corresponding contacts I4I-I5I of the switches are likewiseelectrically connected together in sets, and each set is connected to-athermal switch 69',- which is shown as a contact exposed in the channelof a thermometer, the expansible medium within the thermometer beingconnected to the bus conductor 59 by means of the return conductor 89.Obviously any number of thermostat contacts may be employed, and thenumber of selector switches may be multiplied in order to afford controlof additional solenoid devices 66. If the arm of the switch I33 is setopposite the contact I40, the solenoid 4 will be continuously energized,and if applied to control the apparatus 9, will hold the switch 39closed, so that the valve 2I will be conditioned to direct therefrigerating medium tothe direct cooling coils. Likewise, if the arm ofthe switch I35 is set opposite its contact I 40, the solenoid 54 will beconstantly energized, and the switch 53 will remain closed, thusmaintaining the refrigerating apparatus continuously in operation.Similarly, if the arm of the switch I 31 is set opposite its contactI40, the solenoid 65 will be constantly energized, and the switch 63will remain continuously open, and the heaters will be inoperative.

In like manner, if the arms of the switches I33, I35 and I31 are setopposite the open contact I 52, the solenoids 4|, 54, and 65 will beinactive/and the switches 33 and 53 will remain continuously open, thusdisabling the refrigerating apparatus while the switch 53 will remainclosed, thus maintaining the heaters in continuous operation.

If the arms of the switches I33, I35, and I3'I are set opposite any ofthe contacts I III5I, the solenoids 4|, 54 and 65 will be energized, andthe switches 39 and 53 will be closed, and the switch 63 will open whenthe thermal switch, with which said selector contact is associated,closes. Consequently, as will be obviousgthe selector switches I33, I35,and I3! may be adjusted to cause the control switches 39, 53, and 63 tooperate at any selected temperature within the range provided by theapparatus.

It is thought that the invention, its numerous attendant advantages andinherent functions will be understood from the foregoing description,and it is obvious that numerous changes may be made in the form,construction and arrangement of the partswithout departing from thespirit or scope of the invention, or sacrificing its attendantadvantages, the forms herein shown being only preferred arrangements forthe purpose of illustrating the invention.

circuit control elements, and means operatively connecting each of saidelectrically operable devices with one of the manually adjustableelements whereby said devices may be selectively placed under thecontrol of any of said circuit control elements.

2. 'A control system as set forth in'claim 1 wherein said circuitcontrol elements comprise terminedpath under the influence of increasing5 temperature, said thermometric medium being an electrical conductorand said thermometer means having electrodes disposed in the path ofsaid expanding medium whereby said medium may form electrical contactwith each electrode 10 at-a predetermined temperature.

3. A control system as set forth in claim 1 wherein said circuit controlelements comprise thermometer means embodying a channel, an expansiblecurrent carrying medium adapted to 15 expand and travel in said channelunder the influence of increasing temperature, and an electrode exposedin said channel and adapted to make electrical contact with saidexpansible medium when the same is exposed to temperatures 20 in excessof a predetermined value.

4. A control system as set forth in claim 1 wherein the electricaldevice comprises a solenoid and an associated control element shiftableby the solenoid when the same is energized 25 to perform a controllingoperation.

5. A control system as set forthin claim 1 including means formingapparatus actuated from a prime mover and wherein the electrical controldevice is operatively associated for con- 30 trolling the delivery ofactuating power from the prime mover to said apparatus.

6. A control system as set forth in claim 1 including means formingrefrigerating apparatus wherein a refrigerating medium is delivered to35 a refrigerating element in response to the actuation of a prime moverand wherein the electrical control device is operatively associated withsaid refrigerating apparatus to control the delivery of therefrigerating medium to the refrigerating 40 element. I

7. A control system as set forth in claim 1 including means formingrefrigerating apparatus comprising a plurality of refrigeratingelements,

a prime mover, means to deliver a refrigerating 5 medium to saidelements in response to the actuation of the prime mover, and operablemeans to selectively control the delivery of the refrigerat ing mediumto said elements, wherein said electrical control device is operativelyassociated for 50 controlling said operable means.

8. A control system as set forth in claim 1 including means formingrefrigerating apparatus wherein a refrigerating medium is delivered to arefrigerating element in response to the actua- 55 tion of a prime moverand wherein the electrical control device is operatively associated withsaid prime mover for controlling the operation of the same.

9. A control system as set forth in claim 1 60 including means forming adevice which, when operated, is adapted to produce heat and wherein theelectrical control device is operatively associated with said heatproducing means in order to control the operation of the same. 65

10. A control system as set forth in claim 1 including additionalcircuit-forming means to which said manually adjustable element isconnectible at will, said circuit-forming means being directly connectedwith a power source whereby the electrical control device may bepermanently energized independently of said circuit control elements.

11. A control system as set forthin claim 1 includlng additional meansto which said manually adjustable element is connectible in order toleave the circuit, in which the electrical control device is connected,permanently open so that the same is at all times inactive regardless ofthe of the circuit control elements.

12. A control system as set forth in claim 1 including additional meansto which said manually adjustable element may be selectively connectedin order either to connect the electrical control device in series withthe power source or to leave the circuit permanently open regardless ofthe circuit control elements.

13. A control system for controlling operable apparatus in response tovariable temperature conditions prevailing in a medium at a remotecontrol station comprising the combination with a plurality ofthermostats each adapted to control an electric circuit at apredetermined temperature and each disposed in heat exchangerelationship with the medium at the control station, of a plurality ofmanually adjustable elements selectively connectible at will with any ofsaid thermostats, an electrical control device operation engagepredetermined sets of said circuit control elements; 1

18. A control system as set forth in claim 1 including a second manuallyadjustable device interposedin series between said electrical con- 5trol devices and the manually adjustable elements which are connectiblewith the thermostats, said second manually adjustable deviceelectrically connected with each of said adjustable elements and adaptedto perform a control operation upon the operable apparatus whenenergized, and circuit-forming means connecting each control device witha source of power and connecting said thermostats with said power sourcewhereby each control device may be selectively connected in a seriescircuit including the power source and any desired one of saidthermostats.

14. A control system as set forth in claim 13 including air temperingapparatus having heat adding means for delivering heat to the atmospherebeing tempered and heat subtracting means for removing heat from the airbeing tempered wherein one of said control devices is operativelyassociated with the air tempering apparatus to control the operation ofthe heat adding means while another of said control devices isoperatively associated with the air t mpering apparatus to control theoperation of the air subtracting means.

15. A control system as set forth in claim 13,

including air tempering apparatus having heat exchange means includingheat-adding means and heat-subtracting means for delivering heat to andtaking heat from the atmospherebeing means and still another to controlthe operation of said control means.

16. A control system as set forth in claim 13 including air temperingapparatus having heat exchange means in heat-exchanging relationshipwith the atmosphere being tempered, and control means operativelyassociated with said heat exchange means for varying the rate at whichit performs its heat-exchanging function wherein said electrical controldevices are operatively associated with the air tempering apparatus, oneto control the operation of said heat-exchange means andanother tocontrol the operation of said control means.

17. A control system as set forth in claim 1 wherein said manuallyadjustable elements are ganged together for movement in unison and tocomprising adjustable elements connected each with one of the electricalcontrol devices and 10 connectible at will in any of a plurality ofcircuits including various combinations of the manually adjustableelements which are selectively] connected at will with the circuitcontrol elements.

19. A control system for controlling a plurality 5 of electricallyoperable devices in response to variable temperature conditionsprevailing in a medium at a remote control station comprising thecombination of a plurality of thermostats each, disposedin heat exchangerelationship with the 20 medium at the control station, of a pluralityof manually adjustable elements connectible at will with any of thethermostats, means operatively connecting each of said electricallyoperable devices with one of said manually adjustable eleg5 mentswherebythe devices may be selectively placed under the control of any of saidthermostats, said means comprising manually adjustable means comprisingadjustable elements connected each with one of the electrical controlde- 30 vices and connectible at will with any desired combination of themanually adjustable elements; and means whereby the adjustable elementsof the manually adjustable means may be arranged to connect any'oftheelectrical control 35 devices directly with the power source.

20. A control system for controlling a plurality of electricallyoperable devices in response to variable temperatureconditionsprevailing in a medium at a remote control station comprisingthe 40 combination of a plurality of thermostats each disposed in heatexchange relationship with the medium at the control station, of aplurality of manually adjustable elements connectible at will with anyof the thermostats, means operatively 4 circuit.

21. A control system for controlling a plurality of electricallyoperable devices in response to va- 60 riable conditions prevailing in amedium at a re mote control station comprising the combination, with aplurality of circuit control elements operable in response to variationin thecondition 'of said medium disposed in position to be influenced bythe medium at the control station, of-a plurality of adjustableelements. connectible at will with any of said circuit control elementsand operatively associated each with one of said electrical operabledevices whereby to connect the 7 same with a source of power under thecontrol of any of said circuit control elements, and means with whicheach of said adjustable elements may be selectively associated wherebythe same may be'connected directly with said source of power. 75

22. A control sys em for controlling a plurality,

of electrically operable devices in response to variable conditionsprevailing in a medium'at a remote control station comprising thecombination, with a plurality of circuit control elements operable inresponse to variation in the condition of said medium and disposed inposition to be influenced by the medium at the control station, of aplurality of adjustable elements connectible at will with any of saidthermostats and operatively associated each with one of saidelectrically operable devices whereby to connect the same with a sourceof power under the control of any of said circuit control elements, andmeans with which each of said adjustable elements may be selectivelyassociated whereby the same may be connected directly with said sourceof power or may 'remain entirely disconnected from said power source.

23. A control system as set forth in claim 21, wherein the adjustableelements are ganged for adjustment in unison and interconnected so that,

in each adjusted position, the elements will cooperate each with one .ofa selected set of said circuit control elements.

24. A control system as set forth in claim 21,

wherein the adjustable elements are ganged for 5 adjustment in unison sothat, in each adjusted position, the elements each will connect itsassociated electrically operable device with the power source under thecontrol of one of a selected set of said circuit control elements ordirectly. 10 25. A control system as set forth in claim 21,

wherein the adjustable elements are ganged for adjustment in unison sothat,-in each adjusted position, the elements each will connect itsassociated electrically operable device with the power 15 source, underthe control of one of a selected set of said circuit control elements ordirectly, or will connect its associated electrically operable device inopen circuit.

JOHN LITHGOW. 20

GORDON E. GRAY.

